Thermal treatment of hydrocarbons



Oct. 6, 1936. F. wlNKLER Er AL mi. 0F HYDROCARBONS File@ llarch 18. 1955 ISSUING GAS NVENTORS Fmr: wlNKu-:R HANS HAL-:usan BY i( ToRNeYs Patented Oct.A vv6, 1936 THERMAL TREATMENT HYDROCARBON S Hans Haeuber, Ludwigshafenermany, assignors to I. G. Aktiengesellschaft, Frankforton-the-Main, Germany Fritz Winkler and on-the-Rhine, G Farbenindustrie Application March 18, 1933, Serial No. 661,632

Germany March 22, 1932 2 Claims. (Cl. 196-133) The present invention relatesto the thermal treatment of hydrocarbons.

It has already been proposed to employ elements or the 4th group of the periodic system as catalysts or as coatings for the walls of the reaction vessels inthe thermal treatment of hydrocarbons.

For this purpose, silicon in the free elementary form or in the form oi' alloys has proved especially valuable.

e, when employing carbon it is easy to deposit it in crystalline graphitic form from its gaseous compounds, and while moreover the metals of low melting point of the 4th group of the periodic system, such astin or lead, may be readily applied to metallic substrate., it has only been possible hitherto to prepare with diiiiculty iirmly adherent coatings, impermeable to gases, from the elements of high melting point of the 4th group of the periodic system, such as silicon or titanium, without the assistance of binding agents, especially those of ceramic nature, uxes or the like. y

We have now found that ment of hydrocarbon products in. the solid, liquid or gaseous phase at any pressure in spaces conned by lieat-resistant metals, as for example in tubes of ordinary iron or. for example, of iron alloys containing nickel, no trace of in iurio'us deposition of carbon is operation when the metallic surfaces which come into contract with the substances to be treated are provided wholly or in part with coatings oi elements of the ith group of the periodic systemhaving a melting point between 1000" and 2000 C., which have been prepared by bg in the said elementsin pulverulent form. l

The burning temperature lies ing temperature of the element to be burned in and below the melting point ci metal serving as the carrier material, but above about 950 C. Generally speaking with silicon or titanium it is between 1050 and 1150 C.' and the period during which the elements remain in the glowing zone is trom about 1 to 2 hours. It desired, the

burning may be eilected ina non-oxidizing, preferably reducing atmosphere, as for example in an atmosphereof, nitrogen or hydrogen. In order to obtain a uniform surface 'it is preferableto free the metalllc'surface tov be provided with a coating from the impurities, as for example metal oxides, adhering thereto. burned in is preferably employed in the form of ilnest powder in order to ensure that this material attaches ost closely to the metallic walls. For example it. is desired to provide tubes with an internal protective layer, it has been found preferable in order to obtain a Agood application oi the powder to illl the tubes with powder and toburnthemin averticalposition. Thedurain the thermal treatobtained in continuous below themeltl ,tures between 300 and 1l00 'Ihe material to be tion of the burning or glowing depends on the external conditions, such as the kind of furnace employed, the thickness of the walls of the tubes or, for example when burning in silicon, on the outer surface ofthe tubes, on the thickness oi.

the surrounding layer of powder and the like; in each case the said duration is preferably ascertained by preliminary experiment, for example by proving whether the tube coated with silicon is stable to mineral acids or like methods.

When lemploying ordinary iron tubes as the substr-ata, it is advantageous to make use oi' the known fact that silicon or titanium steels are especially stable to temperature and corrosion and to provide ordinary iron-tubes, for example, with the protective layer both inside and outside, while when working with alloyed steels it is only necessary to apply the-coating to the'surfaces with which the hot substances to be treated come into contact.

By the employment of alloyed steels, as for example of V2A-steel consisting'of about 72 per cent of iron, 7 per cent of nickel, and 20 per cent of chromium, especially rmly adherent coatings are obtained. 4

As processes duced may be for which the apparatus so proused may be mentioned, inter alia,

hydrocarbons, cracking or dehydrogenation of hydrocarbons in the liquid or vapor phase -or polymerization of gaseous or liquid hydrocarbons under the influence of high temperature at atmospheric or increased pressure, as for example the conversion of paramnic or olenic hydrocarbons into aromatic hydrocarbons if desired in the presence of indifferent gases or gases taking part in the reaction. For these treatments tempere- C. depending upon the particular conversion come into question.

The invention will be further explained with reference to the accompanying drawing showing a longitudinal section of a tube in which the said conversions of hydrocarbons may be carried out. It is to be understood, however, that the invention is not restricted tothe particular arrangement shown in the drawing.

In this drawing a denotes an iron tube which not restricted to these Emmple 1 A tube, about 5 meters long, of chromium nickel having an interna narratorv of about `15 is internally coated with a layer b of silicon burnt v -through bic meter of the nal millimeters and an external diameter of about 22 millimeters is lled with ne silicon powder and kept for about an hour at from about 1050 to 1100 C. in a vertical furnace. The tube is then allowed to cool and the silicon powder which has not been "burnt on is removed, the tube then being ready for u se.

The tube is arranged vertically in one o! the usual cracking apparatus for the cracking of petroleums of high boiling point in the vapor phase and is heated externally by re gases so that the temperature m the middle of the tube 1s 780. c.,

at the lower end 750 C. and at the upper end 100 C. From about- 5 to 6 kilograms ci the middle fraction, boiling above 200 C., of a German petroleum are led in the vapor phase per hour the tube with an addition ,oi about 1 cugas obtained in the cracking process which has been freed from condensable cracking products.

. By a single passage through the tube about 18.

to 20 per cent by weight of a benzine boiling below 200 C., about 65 per cent of residual oil which is added to the initial material, about 3 to 5 per cent 'of non-vaporizable heating oil and from 10 to percent of gaseous-constituents are obtained. l

The ilnal gas has approximately the following composition. the percentages being by volume:-

Per cent Per cent C2H6 5.0 mm '7.0 16.0 per cent v(24.21310 4.0

After using the tube continuously for more than two months no injurious deposition of carbon can be detected.

The tube treated with silicon is equally suitable for the d'ehydrogenationv ci saturated benzines for the production of anti-knock motor fuels.

'is led at the rate of 12 liters through a chromium iron tube 1 meter in length` per hour downwards and 15 millimeters in internal diameter which has been treated with silicon internally as described in Example 1 and which is heated in an electric furnace so that the upper ,about 60 centimeters thereof are at 650 centimeters therebelow are atl about 800 C.

From each liter oi the initial gas, 1.58 liters o! a gas are obtained having the following composition, the percentages being by volume:-

Percent CH4 30.90 ("o-lv'a 8.15 CaHs 2.15 C4H1o.... 0.15 NW1' 30.70 CaHa 5.00 -CiHa 0.50 H2 21.40 N: 0.86 O2 0.03 CO 0.16

Furthermore 15.6 per cent by weight of the initial 'gas are converted into liquid products of which about 85 percent consist of products boiling up to 200 C. and mainly composed of aromatic hydrocarbons.

In this case also no inconvenience is caused by the deposition oi carbon even after operation for long periods of time.

If titanium be burnt in instead of silicon, the same results are obtained. Titanium is burnt in also in pulverulent form in a non-oxidizing atmosphere and preferably at a temperature between 1050 and 1150 C.

1. A process for heat-treating a hydrocarbon product at a temperature between 300 and 1100? C., which comprises coniining said product at the said temperature in a space enveloped by a heatresistant metal which is internally coated with a layer substantially consisting of an element of the 4th group of the periodic system having a melting point between l000 and 2000 C. burnt in the said metal in pulverulent form.

2. A process for heat-treating a hydrocarbon product at a temperature between 300 and 1100 C., which comprises coniining said product at the said temperature in aspace enveloped by a metal selected from the group consisting of iron and iron alloys which is internally coated with a layer substantially consisting of an element se- -lected from the group consisting of silicon and titaniumv burnt in the said metalin pulverulent form.

FRITZ WINKLER. HANS y HAEU'BER.

C. while the about 

